"Don't touch that, it's hot."
"It doesn't look hot."
"Hot things are red on Terra." -- Anon Guest
"Uh. Not exactly," said a nearby Human. "Not all red things are hot, and not all hot things are red. For your safety, check for radiant heat," they demonstrated, holding their hand above the surface and gradually approaching touching it until they pulled away. "This one is actually hot. See?"
The tourists huddled together a little. "That is how you test for heat on this Deathworld?"
"Well, yeah. The atmosphere helps distribute heat so there's safe distances and so forth. It's scientific. Only we didn't know it was science before we worked it out." An apologetic grin. "Besides, there's more than red-hot. We have black hot, red hot, yellow hot and white hot in that order. Black-hot can still give you third-degree burns."